Twenty people were killed when a minibus hit a landmine in southern Somalia Thursday, according to local residents and officials.

The incident happened outside Golweyn village, about 22 kilometers from the coastal town of Marka.

Ali Nuur Mohamed, the deputy governor of the Lower Shabelle region, said the bus was en route to Marka when it ran over a mine that was "apparently planted by al-Shabab militants" and meant to target African Union soldiers who protect the Somali government.

Mohamed told VOA's Somali service that of the 21 passengers on board, only the driver survived, with injuries.

“The minibus shattered into pieces and the bodies of the occupants were extensively burned, and beyond visual recognition,” said a resident, who spoke on condition of anonymity for fear of reprisals.

Another resident said he counted the bodies of 20 people.

The AU force in Somalia, AMISOM, has several bases in Lower Shabelle towns, but militants control the rural areas and the roads in between those bases, which they frequently attack.

Mohamed said AMISOM troops often travel in convoys of armored vehicles on the road where the incident occurred. "We suspect that al-Shabab planted the landmine to target them, but unfortunately it hit innocent civilians," he said.

A statement aired by Radio Andalus, al-Shabab's mouthpiece in Somalia, accused the AU of planting the landmine and massacring civilians in the region.

Al-Shabab has been fighting to install its strict version of Islam in Somalia since 2006.